origin-dns: make sure cluster.local DNS server is listed first

This would ensure glibc resolver won't discard this server when existing
DNS server list is longer than 2.
This sed would also update existing configuration, where cluster.local
was appended

roles/openshift_node/files/networkmanager/99-origin-dns.sh

@@ -116,8 +116,9 @@ EOF
       echo "nameserver "${def_route_ip}"" >> ${NEW_RESOLV_CONF}
       if ! grep -qw search ${NEW_RESOLV_CONF}; then
         echo 'search cluster.local' >> ${NEW_RESOLV_CONF}
-      elif ! grep -q 'search.*cluster.local' ${NEW_RESOLV_CONF}; then
-        sed -i '/^search/ s/$/ cluster.local/' ${NEW_RESOLV_CONF}
+      elif ! grep -q 'search cluster.local' ${NEW_RESOLV_CONF}; then
+        # cluster.local should be in first three DNS names so that glibc resolver would work
+        sed -i -e 's/^search \(.\+\)\( cluster\.local\)\{0,1\}$/search cluster.local \1/' ${NEW_RESOLV_CONF}
       fi
       cp -Z ${NEW_RESOLV_CONF} /etc/resolv.conf
     fi